CLARK FREEPORT -- Philippine Institute of Volcanology and Seismology (Phivolcs) Director Renato Solidum revealed that heavy rains that will be brought about by an Ondoy-like typhoon may trigger lahar flows and flooding in Pampanga.
Solidum issued the statement during a briefing with Pampanga-based newsmen belonging to the Capampangan In Media Incorporated (CAMI) at the Bale Balita here on Friday.
“The river gets shallower kasi nasi-silt siya. In short, hindi yan nakakamatay until na magkaroon ka ng sobrang lakas ng ulan and in a short duration iaanod muli yung napondo doon at kung hindi ma-contain ng dike ay baka lumampas,” Solidum said.
In 2008, a study conducted by Phivolcs in Pampanga revealed that continuous rains may repeat massive flooding like the monsoon rains (siyam-siyam) in 1972, which submerged many areas in Central Luzon.
“Yung siyam-siyam, yun ang kailangan nating bantayan. For example, our modeling said if we assume 10 million cubic meters of lahar, which immediately after the eruption ay nangyari yun, so what can happen is that the flow can start depositing above doon sa SCTEX [Subic-Clark- Tarlac Expressway] point sa Delta 5 watch-point. Kung doon nagsimula banda ang deposition baka dito sa may Mancatian area ay abutin doon. So babantayan natin na ang flow at yung ilog ay hindi doon kasi ang tendency ng tubig papunta doon e,” Solidum said.
He suggested “flood-quarrying” or an “engineered-design” quarrying along the Pasig-Potrero river and other adjacent river channels in order to prevent heavy siltation which may threatened several villages inside the FVR megadike.
An estimated 4,000 families reside in several Pampanga towns located inside the megadike which was built during the time of President Fidel Valdez Ramos after lahar remobilized by rain overflowed from the Pasig-Potrero River on October 1, 1995 burying Bacolor town.
“Yung Angeles-Porac road tumatawid doon, bantayan niyo kung bumababaw yan. Kaya ang suggestion nga namin, kung magku-quarry dapat engineered ang design para nakakatulong ka pa sa dredging para ilayo mo doon sa delikadong parte at igitna mo [sa ilog] kasi kung doon parati doon pupunta ang lahar baka umapaw doon,” Solidum said.
Over the past few years, no strong typhoons hit Central Luzon and Pampanga, which may have triggered massive flooding and affected residents inside the megadike and other low-ying areas around the province’s flood -defense structure, according to him.
“Ang issue is apparently now if we just consider the normal rain walang masyadong nangyayari sa loob ng megadike. Pero paano kung lumake, so what will happen to the people who have rebuild inside [the megadike],” Solidum said.
People living inside the megadike should understand the threat, he added.
“Ang point ko lang ay huwag tayong pakakampante. “Logic lang, kinulong mo ang tubig sa isang megadike therefore ang megdike ang purpose niya ay saluhin ang tubig at lahar. Ang main threat diyan ay yung nasa loob. Ngayon, sa lapad naman ng ilog at megadike ay hindi naman natin alam kung saan ang tumbok,” Solidum said.